John Rawls’ Difference Principle, which requires that primary goods--income, wealth, and opportunities--be distributed so as to maximize the primary goods of the least advantaged class, has both a libertarian and a welfarist interpretation. The welfarist interpretation, which fits somewhat more easily with Rawls’ method for deriving principles of justice--rational contractors choosing principles behind the veil of ignorance--and with Rawls’ contention that there is a natural affirmative duty to aid others and to help establish and maintain just institutions, is the orthodox interpretation. But there is scattered, fragmentary evidence for the libertarian interpretation as well. In this article I examine a recent version of the libertarian interpretation put forward by Jeffrey Reiman and discuss its implications as a standard for justice in cooperative arrangements